DropDownList與OnSelectedIndexChanged不顯示數據使用SqlDataReader

Question

我正在一個ASP.NET應用程序，我有一個DropDownList不使用SqlDataReader顯示數據庫中的數據。下面是我的asp.net web表單代碼...

<p> 
<span class="label"> 
<asp:Label ID="Label1" runat="server" Text="Document Number" Font-Size="Small" Font-Bold="True"></asp:Label> 
</span> 
<asp:TextBox ID="numb" runat="server" Width="176px" ReadOnly="true"></asp:TextBox> 
<br /> 
<br /> 
<span class="label"> 
<asp:Label ID="Label2" runat="server" Text="Title" Font-Size="Small" Font-Bold="True"></asp:Label> 
</span> 
<asp:TextBox ID="TextBox1" runat="server" Width="176px"></asp:TextBox><br/> 
<br /> 
<span class="label"> 
<asp:Label ID="Label3" runat="server" Text="Author" Font-Size="Small" Font-Bold="True"></asp:Label> 
</span> 
<asp:TextBox ID="TextBox2" runat="server" Width="176px"></asp:TextBox><br/> 
<br /> 
<span class="label"> 
<asp:Label ID="Label4" runat="server" Text="Account Name" Font-Size="Small" Font-Bold="true"></asp:Label> 
</span> 
<asp:DropDownList ID="name" runat="server" AutoPostBack="true" OnSelectedIndexChanged="OnSelectedIndexChanged" AppendDataBoundItems="true"> 
<asp:ListItem Text="-SELECT-" Value="" /> 
</asp:DropDownList><br /> 
<br /> 
<span class="label"> 
<asp:Label ID="Label5" runat="server" Text="Account Code" Font-Size="Small" Font-Bold="true"></asp:Label> 
</span> 
<asp:DropDownList ID="code" runat="server" AutoPostBack="true"></asp:DropDownList><br /> 
<br /> 

<span class="label"> 
<asp:Label ID="Label6" runat="server" Text="Date" Font-Size="Small" Font-Bold="true"></asp:Label> 
</span> 
<asp:TextBox ID="date" runat="server" Width="176px" ReadOnly="true"></asp:TextBox><br /> 
<br /> 
<asp:Label ID="results" runat="server"></asp:Label> 
</p> 

，下面將我的C＃代碼

if (!IsPostBack) 
      { 
       string CS = ConfigurationManager.ConnectionStrings["conn"].ConnectionString; 
       using (SqlConnection conn = new SqlConnection(CS)) 
       { 
        SqlCommand comm = new SqlCommand("SELECT Account_Name FROM Accounts", conn); 
        conn.Open(); 

        name.DataSource = comm.ExecuteReader(); 
        name.DataTextField = "Account_Name"; 
        name.DataValueField = "Account_Name"; 
        name.DataBind(); 
        OnSelectedIndexChanged(sender, e); 
       } 

       date.Text = DateTime.Now.ToString("MM/dd/yyyy"); 
       LoadDetails(); 
      } 
     } 

     protected void OnSelectedIndexChanged(object sender, EventArgs e) 
     { 
      SqlConnection con = new SqlConnection(ConfigurationManager.ConnectionStrings["conn"].ConnectionString); 
      string account = "SELECT Account_Code FROM Accounts WHERE Account_Name = '" + name.Text + "'"; 
      SqlCommand camd = new SqlCommand(account, con); 
      con.Open(); 

      code.DataSource = camd.ExecuteReader(); 
      code.DataTextField = "Account_Code"; 
      code.DataValueField = "Account_Code"; 
      code.DataBind(); 
      con.Close(); 
     } 

     private void LoadDetails() 
     { 
      using (SqlConnection con = new SqlConnection(ConfigurationManager.ConnectionStrings["conn"].ConnectionString)) 
      { 
       string docNo = Session["doc"].ToString(); 
       string query = "SELECT * FROM [pubs].[dbo].[ReportDocumentNo] WHERE DocumentNo = @docNo;"; 
       SqlCommand cmd = new SqlCommand(query, con); 
       cmd.Parameters.AddWithValue("@docNo", docNo); 
       con.Open(); 
       using (SqlDataReader rdr = cmd.ExecuteReader()) 
       { 
        while (rdr.Read()) 
        { 
         numb.Text = rdr["DocumentNo"].ToString(); 
         TextBox1.Text = rdr["Title"].ToString(); 
         TextBox2.Text = rdr["Author"].ToString(); 
         name.Text = rdr["AccName"].ToString(); 
         code.Text = rdr["AccCode"].ToString(); 
        } 
       } 

      } 

     } 

不管我跑的頁面都是我的文本框被從數據庫中的數據填充除了代碼文本框。我錯過了什麼讓我的代碼文本框顯示數據。謝謝

Answer 1

在aspx頁面Aspx.cs頁面上添加該代碼

<asp:DropDownList ID="ddlMealLocationQT" runat="server" OnSelectedIndexChanged="ddlMealLocationQT_SelectedIndexChanged"></asp:DropDownList> 

protected void ddlMealLocationQT_SelectedIndexChanged(object sender, EventArgs e){ 
    List<int> months = new List<int>(){1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12}; 
    foreach (string month in months) 
    { 
     DropDownListMonth.Items.Add(month); 
    } 
} 

OR

您可以使用DataTextField和DataValueField屬性。

ListControl.DataTextField Property 

    DropDownList1.DataSource = drpdt; 
    DropDownList1.DataTextField="StringValue"; 
    DropDownList1.DataValueField="CurrencyValue"; 
    DropDownList1.DataBind(); 

或者一次添加一個ListItem。

https://www.google.com/search?ie=UTF-8&ufsmps=1&oe=UTF-8&sourceid=navclient&gfns=1&q=ASP%20Tutorials

Answer 2

它總是更好地使用斷開連接的架構，但你的答案這裏是修改

我有使用數據表用於存儲目的

ASPX PAGE 


<asp:DropDownList ID="ddl1" runat="server" AutoPostBack="true" OnSelectedIndexChanged="ddl1_SelectedIndexChanged"></asp:DropDownList> 
      <asp:DropDownList runat="server" ID="ddl2"></asp:DropDownList> 

.CS PAGE

MySqlConnection con = new MySqlConnection(WebConfigurationManager.ConnectionStrings["con3"].ConnectionString); 
    protected void Page_Load(object sender, EventArgs e) 
    { 

     string s = "select distinct IMEI_NO FROM permission"; 
     MySqlDataAdapter ad = new MySqlDataAdapter(s, con); 
     DataTable dt = new DataTable(); 
     ad.Fill(dt); 
     ddl1.DataSource = dt; 
     ddl1.DataTextField = "IMEI_NO"; 
     ddl1.DataValueField = "IMEI_NO"; 
     ddl1.DataBind(); 
     } 



protected void ddl1_SelectedIndexChanged(object sender, EventArgs e) 
    { 
     con.Open(); 
     string s = "select distinct CA_NO FROM permission WHERE IMEI_NO='"+ddl1.SelectedItem+"'"; 
     MySqlCommand cmd = new MySqlCommand(s, con); 
     MySqlDataReader dr = cmd.ExecuteReader(); 
     DataTable dt = new DataTable(); 
     dt.Load(dr); 
     ddl2.DataSource = dt; 
     ddl2.DataTextField = "CA_NO"; 
     ddl2.DataValueField = "CA_NO"; 
     ddl2.DataBind(); 
    }